It was alleged the former Army soldier had shot at them and a helicopter at other times during the stand-off.

Police's internal Ethical Standards Commission is leading the investigation into the shooting, flying in specialist officers, while also liaising with the Crime and Corruption Commission Queensland.

Mossman man Khrys Vignes who was shot by police after a 10-hour siege in Cairns. Picture: Instagram

The Queensland Police Union has also flown staff in to support officers involved and president Ian Leavers said they were "left with no option" but to shoot the gunman.

"All police involved acted bravely. The Queensland Police Union fully supports the actions of all police involved and we are supporting all police involved," he said.

"Out of this incident we are just lucky we don't have murdered or seriously injured police and I know the actions of police ensured that no other person was injured or worse.

"Obviously there were various actions taken by the deceased that will be examined by the Coroner so I am limited in what I can say however I can say all police acted in a highly professional and restrained manner and were left with no option than what occurred."

Police were forced to take lethal action against Mossman man Khrys Vignes at the conclusion to a 10-hour siege on Sunday. Picture: Facebook

A crime scene remained set up at the property yesterday, located just off the Captain Cook Highway near the Yorkeys Knob turn-off.

Police divers took to the waterways, known to be inhabited by crocodiles, on Monday and officers were seen removing items which appeared to be firearms.

Police were locked in a standoff with an armed man on the Captain Cook Hwy who has refused to surrender himself on Sunday. PICTURE: STEWART McLEAN

The Cairns Post understands the divers were supported by police "snipers" on vessels due to the presence of the reptiles.

Local resident Emmy Kunda, who was forced to flee with her family during the siege, confirmed a crocodile up to 3m long resided in the area.

STAND-OFF TIMELINE

4.30am: Police responded to an unlawful entry call at Palm Cove early on Sunday, after reports of a man trying to break into a telecommunication building.

4.30-5am: The accused rams the first police car while avoiding arrest and heads south to Yorkeys Knob.

5.30am: Police set up road stingers at Yorkeys Knob when it's alleged the gunman drove at and struck a young constable.

6am: Gunman rams another police car and evades capture by driving south on the Captain Cook Highway towards Holloways Beach.

6-6.30am: Gunman pulls off the road near Thomatis Creek and fires shots at police and the Rescue 510 chopper.

3.15pm: The gunman is cornered by police in waist-deep water and is shot.